1. Field of the Invention
The present invention relates to an optical module, and more particularly to a fiber pigtail for optical communication system.
2. Description of Related Art
As a telecommunication method, an optical communication system is in practical use, which transmits a wide bandwidth of signal according to an intensity modulation or frequency modulation by the medium of spatial transmission, optical fiber cable, optical lens guide and optical beam guide, employing light as a carrier wave. In this optical communication system, a fiber pigtail is used for converting an input electrical signal into an optical signal, and transmitting it.
In the fiber pigtail, an electric circuit including an optical device (light emitting device and light receiving device), and an optical fiber for transmitting or extracting an optical signal to/from the optical device are coupled so as to form a single unit. The optical device is fabricated in a package, and a ferrule is used for protecting the optical device package and connecting it with other elements. Here, as the light-emitting device, a laser diode of 1.3 .mu.m Fabry perot(FP) is, generally, used and the ferrule is connected to the other elements by welding.
However, since the aforementioned conventional fiber pigtail type FP laser diode has a lower transmission speed of 155 Mbps, it is not suitable for an optical communication module for long-distance transmission. Furthermore, since the ferrule is fixed by 2-point welding, it is difficult to fix the ferrule at the optimal location for the optical axis of the laser diode. This deteriorates the optical coupling efficiency between the laser diode and the optical fiber.